The present invention relates to a head-light system for motor cars comprising at least one but if necessary more, preferably two housings for a head-light and, at least one light-emitting body, wherein the light-emitting body is arranged on the body of the motor car in a translucent outer vessel made advantageously of glass if the housing cannot be hermetically sealed and, in an outer vessel or without it, if the housing can be sealed hermetically. The head-light system of the present invention can be used especially in personal cars, it renders possible a considerable improvement in the conditions of the visibility during driving and ensures an increase of the effectiveness of lighting.
The head-lights systems designed for motor cars are known as systems of European or American-type and, comprise incandescent bodies for emitting light. These bodies are in the form of filaments. According to the European practice, the head-light systems comprise vacuum filled incandescent lamps or, with halogenic filling including one or two filaments because it is assumed that by such solution the light intensity and the effectiveness can be improved. The head-light system represents, however, a high load for the car battery even in the case when incandescent lamps with halogenic filling are used. The power which should be applied to the lamps in a head-light system of known arrangement amounts to as high as 200W which means that the load of the presently used batteries with supply voltage of 12V will go as high as 17 amps.
In the head-light systems of the American-type there is a hermetically sealed inner space wherein a filament of an incandescent body or an incandescent lamp with halogenic filling is used. This is the so-called SB-/sealed-beam/system. It can be advantageous to use two filaments or two incandescent lamps in a unit.
In the head-light systems produced for the European markets, the filaments lie mostly in lateral and in axial directions as well. This solution shows the advantage that a double function, i.e. driving lights and passing lights can be put into the same unit. The well-known incandescent lamps developed for this purpose comprise two filaments taking up a supply of 45/50W and giving a light output as high as 700/450 lm. When using incandescent lamps with halogenic filling there are also two filaments and, the power supply amounts to as high as 60/55W transformed into a light output of 1650/1000 lm value.
The special filaments used in the incandescent lamps with halogenic filling ensure small dimensions of the head-lights and a high light output in form of a highly concentrated light beam. The concentrated light beam is undesired during passing and, therefore, the beam should be scattered by the use of optical or other means. In the known head-light systems prismatic parts are used in the sealing glass of the lights.
When analysing the conditions of driving in the night, the concentrated light beam shows the disadvantages that due to the concentration the dimensions of the beam are small in cross directions and, therefore, the driver can see only a limited part of the environment. However the light beam is capable of clearly showing the road-block but the environment is hardly visible and, therefore, it is difficult to quickly and reliably make conclusions about the type of road-blocks. If better visibility conditions are to be given for the driver in the night traffic, then more intensive and wider light beam is to be emitted by the head-lights of his car. In the article of J. B. de Boer and D. A. Schreuder published in the "Lichttechnik" /No. 9 in 1969/a detailed analysis can be found about the different aspects of the use of incandescent lamps with halogenic filling in the field of lighting technics for motor cars. In the article the authors comment that incandescent lamps with halogenic filling of higher light output are capable of increasing the surface illuminated by the head-lights. By means of the known incandescent lamps with halogenic filling it has been possible to improve the light output in some directions, however, no improvement could be made in the full cross-section.
It is desirable therefore, to increase the road surface which is well illuminated by the head-lights of the car, but this can be done by means of the conventional incandescent lamps only by increasing the power supply. This can not be realized, therefore, the choice remaining is to construct a head-light system wherein light sources of higher light output should be used. However, when safety aspects are taken into account, such as a head-light should not emit a light beam which can dazzle the drivers of the motor cars driving in opposite direction. Then such solution remains undesirable.
It is understood that an increased domain of good illumination during driving, and improved lighting of the road surface can be attained by means of a higher number of head-light units, and/or by using incandescent lamps of higher power supply accompanied by use of a prismatic domain on the glass element sealing the head-light unit. The prismatic domain should be used for scattering the light in a domain as to decrease the light intensity during approaching a car driving in the opposite direction before passing.
None of the above mentioned solutions is acceptable from energy considerations because they require to increase the power input. It is also unacceptable under the international rules which demand lighting the power of the incandescent lamps used in head-light systems.